The present invention relates generally to systems for diverting aquatic life over or around structures that inhibit migration of anadromous species along a waterway.
Dams and other structures are placed in waterways to redirect natural water flow for other uses, such as power generation, industrial processes, water supplies, and agricultural development. The redirected water can be employed with various apparatus or systems, such as turbines, pumps, cooling systems, irrigation canals, and water treatment systems, to name a few. The redirected water typically travels through one or more intakes or spillways positioned below or at the water surface. This redirection of water creates a risk that fish and other aquatic life will be injured or killed by the various apparatus in the path of the redirected water, or killed or injured in the eventual use of the redirected water. For example, fish can be entrained into the intake or impinged onto the intake screen protecting a turbine intake that is in the path of the redirected water flow.
The above problems are particularly acute with respect to fish that must migrate to the sea as a critical part of their life history. In addition to other anadromous species, the salmon smolt has had particular attention devoted to preserving its migratory capabilities over or around structures that redirect flow in the waterway. This focus is further magnified when the aquatic species is protected under the Endangered Species Act as is the salmon smolt.
Salmon smolts have a natural instinct to travel down the waterway in which they inhabit to the sea. The natural habitat of a smolt in a non-obstructed flowing waterway is relatively noisy. When a dam is in the waterway, the habitat of the smolt is relatively still and quiet upstream of the dam. However, the environment in the waterway near the dam structure includes many sounds along with rapidly changing accelerating and decelerating flows, which is further exasperated if the dam has hydroelectric machinery such as turbines. This creates a sudden change in the environment from a peaceful one to a very disruptive one. These noises and changing flow patterns are unfamiliar to the smolt that is accustomed to the waterway habitat in which it previously lived. Current attempt to bypass smolts around the dam have met with marginal success perhaps due to the abrupt change in environment near the dam.
Although smolts feel a natural urge to continue downstream toward the sea, the disturbances caused by the dam that is in the waterway create hesitation in the smolt and disrupt migratory behavior. This disruption can result in the loss of salmon population unless adequate paths around the structure are provided for the smolts.
One example of a fish diversion apparatus is provided in U.S. Pat. No. 5,385,428. The ""428 patent describes a diversion apparatus 20 that requires floors 30a and 30b, sidewalls 36a and 36b, and roof 72, each of which is constructed of reinforced concrete, structural steel, or steel plate. The apparatus 20 is built into a substrate 70 which may consist of rock, soil, or sand depending on site conditions. One drawback to the apparatus of the ""428 patent is that it can be expensive to construct since apparatus 20 requires its construction in the waterway. Apparatus 20 also contributes to further disruption of the waterway habitat since it is permanently located in the waterway upstream of the dam. Another drawback is that the height of apparatus 20 could become large as the depth of the waterway increases, which further increases cost and complexity.
While there have been attempts in the prior art to provide systems that route smolts and other aquatic life around foreign structures in the waterway, there remains room for improvements. There remains a need for a system that takes advantage of smolt behavior near the dam in order to facilitate this diversion. There also remains a need for a system that makes the transition of smolts and other aquatic life around the dam less traumatic and less frightening. The system should be readily adaptable for use with existing structures, and should also be able to be employed with the design of new structures. Furthermore, the system should be relatively inexpensive. The present invention is directed to meeting these needs, among others.
The present invention is directed to a fish diversion apparatus to divert smolts and other aquatic species around a dam or other waterway structure.
Several characteristics of smolt behavior immediately upstream of existing dams have been noted in consideration of the design of the system of the present invention. One characteristic is that smolt behavior becomes increasingly complex in both horizontal and vertical movement as the dam structure is approached. Another characteristic is that smolts typically face upstream for swimming control while traveling downstream. Smolts also migrate relatively high in the water column as the dam is approached, generally staying within 10 meters or less below the water surface. Further, the speed with which the smolts swim decreases near the dam structure. The present invention considers this behavior in the design of a diversion system to direct smolts around dam structures by creating a substratum to gently guide the smolts to a bypass near the water surface and away from the turbines or other harmful structures of the dam. It is further believed that the system of the present invention may have application in diverting fish around structures other than dams and also application with aquatic species other than salmon smolts.
According to one aspect of the present invention, there is provided a fish diversion apparatus that diverts fish and other aquatic species around a structure in the waterway. The apparatus includes a frame extending between a top end that is oriented towards the water surface and a bottom end that is oriented below the water surface. The frame supports a number of bar screen panels below the water surface. The bar screen panels allow water to flow through the panels from an upstream side to a downstream side of the bar screen panels. A flow scoop extends from the bottom end of the frame to divert the fish upwardly along the upstream face of the bar screen panels. The flow scoop also discourages the fish from moving down the screen and below the frame. The fish are captured in a fish diverter device that is provided adjacent the top end of the frame in communication with the upstream side of the bar screen panels.
According to another aspect of the invention, a fish diversion system is provided to divert fish around a structure that extends below the surface of a body of water. The system includes a frame that extends between a top end oriented towards the water surface and a bottom end oriented below the water surface. The frame supports a number of bar screen panels below the water surface. The bar screen panels allow water to flow therethrough. At the top end of the frame, a fish diverter device is provided that is in communication with the upstream side of the bar screen panels. The fish diverter device includes an incline panel pivotally attached at one end to an upper end of the frame and/or the bar screen panels. An entry portion to a collection channel is pivotally attached at the other end of the incline panel.
Another aspect of the invention provides a method for diverting fish around a structure in a waterway. The fish and water flow are directed by a flow scoop upwardly along the upstream face of a number of bar screen panels and into a collection device.
These and other aspects, forms, embodiments, features, objects and advantages of the present invention will be apparent in the detailed description that follows.